1. Field of the Invention
The present invention relates to a method and apparatus for reducing nitrogen dioxide emissions in a flueless heating appliance or heater, i.e. a heating appliance or heater in which fumes produced by the combustion of the fuel with which the heating appliance or heater is supplied are discharged directly into the environment in which the appliance is located.
2. Prior State of the Art
In this type of heating appliance or heater it is essential for the toxic emissions, in particular carbon monoxide (CO) and nitrogen oxide (NO2), to be kept as low as possible; it is also essential that the percentage of oxygen in the environment in which the heating appliance or heater is located does not fall below a preset level.
This is essential in order to safeguard health of persons who are in the nearby environment to the heater.
Particular attention is paid to minimising NO2 emissions, which, until now, has not been satisfactorily achieved.
Known flueless heating appliances include a gas combustion system generally consisting of a pressure adjuster, a gas valve, a burner, a flame igniter, a monitor and a conduit supplying the gas fuel.
The above system is contained in a heater body provided with a deflector for channelling the combustion products outside and reducing the temperature of the heater body by shielding it.
These heating appliances or heaters can be provided with different types of burners, for example, convection burners or radiant burners, that are aspirated naturally or with assisted aspiration. The gas valve may be manually controlled or thermostatically controlled with finite or variable heat adjustment that is manually or remotely controlled. These heating appliances or heaters generally operate without electric power but can be provided with electric ignition and fans.
Flueless heating appliances or heaters are also known which contain pieces of artificial wood that are actually made of ceramic fibre, cement or a mixture of cement and ceramic fibre and are used to give the illusion of the combustion of pieces of wood. The combustion systems used in this type of heating appliance or heater are substantially the same as those mentioned before.
The prior-art flueless heating appliances or heaters, despite the progress made over the last few years, have not yet effectively solved the problem of excessive NO2 emissions.